Primary Mechanism
These are fundamental or essential mechanisms. Without these mechanisms, it is practically impossible to produce a fabric. The primary motions can further be divided as shedding, picking and beat up motions. The shedding opens the warp sheet into layers to facilitate passage of shuttle. The picking motion causes the shuttle carrying weft to be propelled from one end of loom to another. The beat up motion lays the previously laid weft to the fell of the cloth.It is for the reason that these mechanisms are called “Primary mechanisms”. The primary mechanisms are 3 in number.

Secondary Mechanism
These mechanisms are next in importance to the primary mechanisms. If weaving is to be continued, these mechanisms are essential. The secondary motions comprise of take up and let off motions. The take up motion helps to wind the cloth on to the cloth roller and also influences the pick density in the cloth. The let off motion helps to let the warp from the weaver’s beam at an uniform rate thus maintaining the warp tension constant throughout the weaving process.So they are called “Secondary mechanisms”. They are

1. Take-up motion
2. Let-off motion

Auxiliary Mechanism
To get high productivity & good quality of fabric, additional mechanisms, called “Auxiliary mechanisms” are added to a plain power loom. The auxiliary mechanisms are useful but not absolutely essential. The auxiliary motions consist of the warp stop motion, weft stop motion and warp protector motion. The warp stop motion is used to stop the loom in the event of warp breakages. This is necessary to prevent fabric defects such as missing ends and floats. The weft stop motion is used to stop the loom in the event of weft exhaustion or weft breakages. This is necessary to prevent missing weft threads called cracks, in the fabric. The warp protector is used to prevent multiple warp thread breakages in the event of shuttle getting trapped in the middle of the warp sheet. These are listed below:

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